I am sorry to hear that you had a car accident 4 months ago, and you were knocked unconscious. That must have been a pretty bad accident with a lot of force to cause a loss of consciousness. I am also sorry to hear that you have had some persistent bumps on your head and neck that have not gone away after the accident. I am happy to give you some of my initial thoughts about what might be going on, and some of the things that I have seen in my experience, but ultimately I am going to recommend that you make an appointment to be evaluated by an ENT (Ear Nose Throat) physician to be evaluated. They will be able to take more of a history and examine you, which is required for an accurate differential diagnosis and proper work-up. I am not sure if you had significant head trauma, but I have seen patients that went through their windshields in an accident that had retained fragments of glass and gravel that were in their scalp that worked their way out over time. More probable is that you had abrasions on the skin of your face or scalp (causing a low grade infection) which in turn caused inflammation of the lymph nodes in your scalp and neck. It can take quite a long time for these lymph nodes to go down. The ENT should be able to examine you and tell you if this is what is going on.